For a while I have been pondering how to explain this annoyance in a good way until I saw a comment the other way on some website I randomly visited so I'll just repost it. He puts it so well:
Leisuresuit Larry on March 21, 2011 at 10:59 wrote:Disqus is evil and wants to sell your personal information once you've signed up. Disqus prevents people from posting "real" comments sicnce everything you say is linked back to your account. I don't care for this level of transparency - how can people be okay with giving up their anonymity? I guess if your the hardcore blogger than it's cute to try and help you keep your own comments organized. But for all others, Disqus is a real headache.